During surgery, or as a result of trauma, tissue volume can be removed or altered, and an open or dead space is created within the tissue that was previously attached to other tissue. The very small blood vessels that previously ran from the underlying tissue (i.e., muscle, connective tissue) to the overlying tissue (i.e., skin, muscle) can be cut or damaged. Although these vessels usually do not cause significant blood loss, they do allow escape of blood serum into the area. Human blood serum contains about ninety-three percent water and about seven percent protein (mostly albumin).
Following surgery or due to trauma, there can also be resulting tissue damage, regardless of how careful the surgeon is. This tissue damage results in cellular death, and the body's natural defense reaction is an inflammatory one. Because of the inflammation, cell death, and increased vascular permeability, fluid can also accumulate in the operative space. The larger the operative space, the greater is the potential for internal fluid collection.
The body can resolve the accumulation of fluid over time, if there is some form of natural drainage, and if there is not continued irritation to the area, and if circulation to the area is sufficient, and if the person is in good health or the volume of fluid collection is itself not too large.
If, for whatever reason, the body is unable to itself efficiently absorb the excess fluid, a seroma can occur. A seroma is defined as a sterile accumulation of blood serum in a circumscribed tissue location or operative space. A seroma is not by definition an “infection;” it does not necessarily involve the presence of white blood cells, bacteria, and the breakdown products of both. A seroma is fluid and blood serum that has accumulated in a dead space in the tissue. A seroma is the result of tissue insult and the product of tissue inflammation and the body's defense mechanisms.
Seromas commonly develop following drain removal or when fluid is produced at a greater rate than it is absorbed. Conventional wound management techniques are commonly applied when a seroma becomes a clinical concern. Placement of a seroma catheter or additional drain, as well as repeated or serial drainage of a seroma, may be required. A seroma or fluid collection is by far the most common complication in surgery today. Such complications result in a significant amount of lost income to patients, as well as expenses to insurers and physicians who have to care for these patients that require serial drainage. Such complications also delay wound healing, may entail additional surgical procedures, and ultimately delay the patient's return to work and routine functional activity. Seroma management can also be costly and, further, can place health care workers to additional needle exposure risks and related outcomes such as hepatitis, etc.
The aim of wound management in both chronic and acute situations is to assist the natural process and prevent further complications such as infection, slough, necrosis formation, and chronic seroma cavities. Maintenance of the optimum wound healing environment is essential, ensuring the wound is kept moist and warm. Wound care products strive to achieve these results and, in turn, help to promote rapid wound closure.
Fluid drainage can be as simple as creating an opening at the lowest edge of the seroma, and keeping this open and clean to allow continued drainage. A clinically accepted way to deal with a seroma that does not appear to be resolving on its own, is to install a continuous drain system, coupled with treatment with antibiotics to prevent infection while the continuous drain system is in use. There are currently numerous types of wound drains on the market, most of them utilizing some form of tubing to withdraw fluid from the wound until the body can resorb the fluid without assistance. A continuous drain system allows the fluid to continuously escape until the body can complete the healing process on its own.
A representative prior art continuous drain system can comprise an implanted device such as a piece of rubber tubing (Penrose drain) (as shown in FIG. 1), which provides dependent gravity drainage or responds to a negative suction force generated by a manual closed suction bulb. These types of drains constitute the most common devices currently available. The problem with these devices is that, although they may drain fluid, fluid drainage is limited to fluid directly around the drain itself. As a result, current drains may manage fluid collection, but they do not effectively clear all of the fluid in the space and, more importantly, they do not clear enough fluid to effectively seal down and close off the dead space.
Another representative prior art continuous drain system, which is currently approved for external use only, can take the form of an externally applied device comprising a piece of foam with an open-cell structure, which coupled to one end of a drain tube (see FIG. 2). The foam is placed externally on top of the wound or skin, and the entire external area is then covered with a transparent adhesive membrane, which is firmly secured to the healthy skin around the wound margin. The opposite end of the drain tube is connected to a vacuum source, and blood or serous fluid are drawn from the wound through the foam into a reservoir for subsequent disposal. Among the numerous names this prior art system is called are “Vacuum Assisted Closure device” or VAC devices. Conventional VAC devices, however, are only approved and used for external wounds only. Conventional VAC devices are not approved or used for internal wounds or operative sites.
Current wound drain devices assemblies at times do not remove a substantial amount of fluid from within a wound and have other performance issues. For example, external VAC devices clear fluid directly around external wounds (as FIG. 3 shows), and they are limited to the application to external wounds only. They leave the remainder of the wound site or operating space open and filled with fluid.
Furthermore, the clinical use of external VAC devices may not make wound drainage more cost-effective, clinician-friendly, and patient-friendly.
For example, the foam structures and adhesive membranes associated with conventional practices of external VAC need to be periodically removed and replaced. Currently, dressing changes are recommended every 48 hours for adults with non-infected wounds, and daily for infants and adolescents. Current techniques place the foam material in direct contact with granulating tissue. Removal of the foam structures in the presence of granulating tissue and the force of pressure on the wound bed that this removal can cause pain or discomfort. The sponge can also de-particulate and remain in the wound. Furthermore, the multiple steps of the conventional external VAC procedure—removing the adhesive membrane, then removing the old foam structures, then inserting the new foam structures, and then reapplying the adhesive member along the entire periphery of the wound—are exacting, tedious and time consuming. They only prolong pain or discomfort, and cause further disruption to the patient, and also demand dedicated nursing time and resources.
Furthermore, to function correctly, the adhesive membrane applied over the foam wound structures must form an airtight seal with the skin. Obtaining such a seal can be difficult, particularly in body regions where the surrounding skin is tortuous, and/or mucosal and/or moist.
Furthermore, prolonged wearing of wet dressings can cause further breakdown and maceration of the surrounding skin thereby increasing the wound size. This can cause further discomfort to the patient, and the exudate can often be offensive in odor and color causing further embarrassment to the patient. This may, in turn, require more numerous dressing changes and re-padding throughout the day, which is disruptive to the patient and costly both in terms of nursing time and resources.
Furthermore, since the membrane and the material of the foam structures are both in direct contact with tissue, tissue reactions can occur.
There remains a need for improved drains, systems, devices, methods that are cost-effective, patient-friendly, and clinician-friendly.